Impact adapter for transfer of impacts and rotation from an impact rock drilling machine to a drill string

ABSTRACT

An impact adapter for transfer of impacts and rotation from an impact rock drilling machine to a drill string has a first end ( 5 ) connectable to a drill string, and a second end provided with ridges ( 7 ) and interposed grooves ( 8 ) for transferring rotation. The grooves ( 8 ) at the end ( 9 ) directed away from the first end ( 5 ) of the impact adapter ( 2 ) are widened in a direction away from the first end ( 5 ) of the impact adapter.

The present invention relates to an impact adapter for transfer ofimpacts and rotation from an impact rock drilling machine to a drillstring.

In previously known impact adapters ridges and grooves at the rear endof the impact adapter are used for transferring torque to a drill stringfrom a driver journalled in the rock drilling machine. Because ofmanufacturing tolerances one has a certain play between the impactadapter and the driver in order to allow the axial movement caused bythe impacts of the rock drilling machine against the impact adapter.This results in the impact adapter coming more or less obliquely in thedriver. This oblique position in combination with the relative axialmovement between the driver and the impact adapter often gives rise tobreakage of one or more of the ridges adjacent the rear end of theimpact adapter.

The present invention, which is defined in the subsequent claims, aimsat decreasing the problem with ridge breakage by decreasing the surfacepressure between impact adapter and driver. This is achieved by makingthe grooves between the ridges on the impact adapter wider at the rearend of the impact adapter.

An embodiment of the invention is described below with reference to theappended drawing in which

FIG. 1 shows a section through a part of an impact rock drillingmachine.

FIG. 2 shows a part of the impact adapter according to the invention.

FIG. 3 shows a view from the right in FIG. 2.

The rock drilling machine shown in the drawing comprises a machinehousing 1, consisting of several connected parts, in which an impactadapter 2 is displaceably arranged in a driver 4. The driver 4 isrotatable by means of a not shown motor. The driver transfers torque tothe impact adapter 2 via splines 6 comprising ridges 7 and interposedgrooves 8 at a second end of the impact adapter 2. The impact adapter 2is at the front end, a first end, provided with a thread 5 forconnection to a drill string in the usual way. The grooves 8 are at theend 9 directed away from the first end of the impact adapter widenedaway from the first end, which is shown by means of the angle v.Furthermore the ridges 7 have at the rear end 9 a somewhat smallerradial extension, which is shown by means of the angle u. Through thisit is achieved that obliqueness between impact adapter and driver givesa lower surface pressure than what is obtained without these widenedgrooves. In the drawing the ridges 7 are formed in the same way at theend directed away from the end 9. The grooves widened towards the endsare suitably produced by feeding the milling tool milling the grooves 8somewhat towards the centre of the impact adapter at the groove ends.

1. Impact adapter for transfer of impacts and rotation from an impactrock drilling machine to a drill string comprising a first end (5) forconnection to a drill string and a second end provided with ridges (7)and interposed grooves (8) for transfer of rotation, characterized inthat the grooves (8) at the end (9) directed away from the first end (5)of the impact adapter (2) are widened in the direction away from thefirst end (5).
 2. Impact adapter according to claim 1, characterized inthat the ridges (7) at the end (9) directed away from the first end (5)of the impact adapter (2) has a smaller radial extension.